1. Field of the Invention
The present invention relates to an ink cartridge and an ink filling apparatus.
2. Description of Related Art
As a kind of ink cartridge, an ink container for an inkjet printhead is disclosed in JP-A-5-338198, for instance. The ink container includes a cylindrical member as a mainbody, and an ink outflow port is formed in a wall of the cylindrical member at an axial end thereof. The ink container further includes a piston that is air-tightly and slidably fitted in the cylindrical member.
It can be considered that the ink container is filled with an ink such that the ink is fed into the cylindrical member through the ink outflow port, with the piston being slid in a direction away from the wall in which the ink outflow port is formed.
Meanwhile, JP-U-5-44801 discloses an adjusting apparatus for a packaging machine which adjusts an amount of a filling material supplied into a container or a package. The adjusting apparatus includes a filling cylinder, a piston slidably or reciprocably fitted in the cylinder, an L-shaped lever or a bell crank having a slot extending in and along one of two arms thereof and a screw shaft disposed in the slot parallel to a longitudinal direction of the slot. A slider is slidably fitted in the slot and threadably engaged with the screw shaft, and the piston is connected to the slider via a piston rod extending downward from the piston out of the filling cylinder, and a connecting rod. The arm of the bell crank in which the slot extends is disposed under the filling cylinder to be swingable or turnable around a pivot shaft.
When the filling cylinder is to be filled with a liquid as the filling material the arm of the bell crank is swung or turned around the pivot shaft away from the filling cylinder in order to lower the piston in the filling cylinder to introduce the liquid into the filling cylinder from a port formed in an upper wall of the filling cylinder.
The adjusting apparatus has a drawback that the piston rod and the connecting rod are connected to each other such that each of the piston rod and the connecting rod is pivotable about an axis that corresponds to a connecting point between the piston rod and the connecting rod, and thus an amount of movement of the piston is not simply or linearly proportional to an angle of swinging or turning of the bell crank.
Accordingly, an amount of the liquid poured out from the filling cylinder toward a nozzle from which the liquid is ejected into the package, is not simply or linearly proportional to the angle of the swinging or turning of the bell crank. Thus, controlling the adjusting apparatus is difficult, resulting in lower accuracy and precision of the adjustment of the amount of the filling material.
The adjusting apparatus is disadvantageous also in the complex connecting structure between the piston and the bell crank. That is, the piston is connected to the piston rod that is connected to the connecting rod. that is in turn connected to the slider fitted in the slot of the bell crank.